Re: Security concern?
"Also, at a cost of £11bn, how far would that go reducing real demand by, say, switching street lights to LED or insulating more homes etc...?"
You're quite right that smart meters are a waste of money that could be better spent on insulation measures. £11bn would insulate every remaining cavity wall in the land, every under-insulated loft, and still leave enough over to insulate 700,000 solid wall homes with external wall insulation. Or, you could leave the cavity walls, and do two million solid wall homes and top up insulation in every loft.
LEDs save energy in buildings because they displace less efficient sources like halogens, CFLs and incandescent bulbs. But that's not true in streetlighting. LED streetlighting is certainly a big improvement over low pressure sodium lamps in terms of light quality and a bit of an improvement in bulb life, but in energy terms it is hardly any better - the luminous efficiency of sodium vapour lamps is around 100 lumens per watt, and that's about the same as most current generation LED streetlight luminaries (both technologies efficiency vary but within a similar range). The top LED makers have developed diodes capable of 300 lumens per watt, but it'll be several years before they reach service, because in streetlighting you need to have long life certainty, and that involves long testing, and not pushing performance envelopes. So expect the UK to spend billions on current generation LED streetlights, and then to replace them all again starting 2022 because the ones we've fitted are using three times as much energy as their replacements will.